/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.g2d.routing.spatial;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Random;

import org.simantics.g2d.routing.algorithm1.Rectangle;

/*
 * 2-dimensional R-tree
 */
public class RTree {

	public static final int MAX_ENTRIES = 7;
	public static final int MIN_ENTRIES = 3;
	public static final int MAX_ENTRIES_AFTER_SPLIT = MAX_ENTRIES - MIN_ENTRIES + 1;
	
	static interface INode {
		void search(Rectangle rect, IRectangleProcedure proc);
		boolean intersects(Rectangle rect);
		Split add(Rectangle rect, Object value);
		
		double[] getRectangles();
		Object[] getChildren();
		void setCount(int count);
		
		Rectangle findBounds();
	}
	
	static class Split {		
		double oldX0, oldY0, oldX1, oldY1;
		double newX0, newY0, newX1, newY1;
		INode newNode;
		
		public Split(double oldX0, double oldY0, double oldX1, double oldY1,
			double newX0, double newY0, double newX1, double newY1,
			INode newNode) {
			this.oldX0 = oldX0;
			this.oldY0 = oldY0;
			this.oldX1 = oldX1;
			this.oldY1 = oldY1;
			this.newX0 = newX0;
			this.newY0 = newY0;
			this.newX1 = newX1;
			this.newY1 = newY1;
			this.newNode = newNode;
		}				
		
	}
	
	class Node implements INode {
		double[] rectangles = new double[MAX_ENTRIES*4];
		INode[] children = new INode[MAX_ENTRIES];
		int count = 0;
		
		public void search(Rectangle rect, IRectangleProcedure proc) {
			double x0 = rect.x0;
			double y0 = rect.y0;
			double x1 = rect.x1;
			double y1 = rect.y1;
			for(int i=0,ad=0;i<count;++i,ad+=4)
				if(x1 >= rectangles[ad] && x0 <= rectangles[ad+2] &&
					y1 >= rectangles[ad+1] && y0 <= rectangles[ad+3])
					children[i].search(rect, proc);			
		}
		
		public boolean intersects(Rectangle rect) {
			double x0 = rect.x0;
			double y0 = rect.y0;
			double x1 = rect.x1;
			double y1 = rect.y1;
			for(int i=0,ad=0;i<count;++i,ad+=4)
				if(x1 >= rectangles[ad] && x0 <= rectangles[ad+2] &&
					y1 >= rectangles[ad+1] && y0 <= rectangles[ad+3])
					if(children[i].intersects(rect))
						return true;
			return false;
		}

		@Override
		public Split add(Rectangle rect, Object value) {
			double x0 = rect.x0;
			double y0 = rect.y0;
			double x1 = rect.x1;
			double y1 = rect.y1;
			
			int bestId = -1;
			double bestArea = 0.0;
			double bestAddition = Double.POSITIVE_INFINITY;
			for(int i=0,ad=0;i<count;++i) {
				double x0b = rectangles[ad++];
				double y0b = rectangles[ad++];
				double x1b = rectangles[ad++];
				double y1b = rectangles[ad++];
				double area = (x1b-x0b)*(y1b-y0b);
				if(x0 < x0b) x0b = x0;
				if(y0 < y0b) y0b = y0;
				if(x1 > x1b) x1b = x1;
				if(y1 > y1b) y1b = y1;
				double addition = (x1b-x0b)*(y1b-y0b) - area;
				if(addition < bestAddition || (addition==bestAddition && area < bestArea)) {
					bestId = i;
					bestArea = area;
					bestAddition = addition;					
				}
			}
			Split split = children[bestId].add(rect, value);
			if(split == null) {
				if(bestAddition > 0.0) {
					int ad = bestId * 4;
					rectangles[ad] = Math.min(rectangles[ad], x0); ++ad;
					rectangles[ad] = Math.min(rectangles[ad], y0); ++ad;
					rectangles[ad] = Math.max(rectangles[ad], x1); ++ad;
					rectangles[ad] = Math.max(rectangles[ad], y1);
				}
			}
			else { 
				int ad = bestId * 4;
				rectangles[ad] = split.oldX0; ++ad;
				rectangles[ad] = split.oldY0; ++ad;
				rectangles[ad] = split.oldX1; ++ad;
				rectangles[ad] = split.oldY1;
				if(count < children.length) {	
					ad = count * 4;
					rectangles[ad] = split.newX0; ++ad;
					rectangles[ad] = split.newY0; ++ad;
					rectangles[ad] = split.newX1; ++ad;
					rectangles[ad] = split.newY1;
					children[count++] = split.newNode;
				}
				else {
					Node newNode = new Node();
					findNodeSeeds(rectangles, children, 
						new Rectangle(split.newX0, split.newY0, split.newX1, split.newY1), 
						split.newNode, newNode.rectangles, newNode.children);
					return splitNode(this, newNode);
				}
				
			}
			return null;
		}

		@Override
		public Object[] getChildren() {
			return children;
		}

		@Override
		public double[] getRectangles() {
			return rectangles;
		}

		@Override
		public void setCount(int count) {
			this.count = count;			
		}

		@Override
		public Rectangle findBounds() {
			double x0 = Double.POSITIVE_INFINITY;
			double y0 = Double.POSITIVE_INFINITY;
			double x1 = Double.NEGATIVE_INFINITY;
			double y1 = Double.NEGATIVE_INFINITY;
			for(int i=0;i<count;++i) {
				int ad = i * 4;
				double x0a = rectangles[ad++];
				double y0a = rectangles[ad++];
				double x1a = rectangles[ad++];
				double y1a = rectangles[ad++];
				Rectangle rect = children[i].findBounds();
				if(rect.x0 != x0a)
					throw new RuntimeException("x0");
				if(rect.y0 != y0a)
					throw new RuntimeException("y0");
				if(rect.x1 != x1a)
					throw new RuntimeException("x1");
				if(rect.y1 != y1a)
					throw new RuntimeException("y1");
				x0 = Math.min(x0, x0a);
				y0 = Math.min(y0, y0a);
				x1 = Math.max(x1, x1a);
				y1 = Math.max(y1, y1a);
			}
			return new Rectangle(x0, y0, x1, y1);
		}
	}
	
	class Leaf implements INode {
		double[] rectangles = new double[MAX_ENTRIES*4];
		Object[] children = new Object[MAX_ENTRIES];
		int count = 0;
		
		public void search(Rectangle rect, IRectangleProcedure proc) {
			double x0 = rect.x0;
			double y0 = rect.y0;
			double x1 = rect.x1;
			double y1 = rect.y1;
			for(int i=0,ad=0;i<count;++i,ad+=4)
				if(x1 >= rectangles[ad] && x0 <= rectangles[ad+2] &&
					y1 >= rectangles[ad+1] && y0 <= rectangles[ad+3])
					proc.call(
						rectangles[ad], rectangles[ad+1], 
						rectangles[ad+2], rectangles[ad+3], 
						children[i]);			
		}
		
		public boolean intersects(Rectangle rect) {
			double x0 = rect.x0;
			double y0 = rect.y0;
			double x1 = rect.x1;
			double y1 = rect.y1;
			for(int i=0,ad=0;i<count;++i,ad+=4)
				if(x1 >= rectangles[ad] && x0 <= rectangles[ad+2] &&
					y1 >= rectangles[ad+1] && y0 <= rectangles[ad+3])
					return true;
			return false;
		}

		@Override
		public Split add(Rectangle rect, Object value) {
			if(count < children.length) {
				int ad = count*4;
				rectangles[ad++] = rect.x0;
				rectangles[ad++] = rect.y0;
				rectangles[ad++] = rect.x1;
				rectangles[ad] = rect.y1;
				children[count++] = value;
				return null;
			}
			else {
				Leaf newLeaf = new Leaf();
				findNodeSeeds(rectangles, children, rect, value, newLeaf.rectangles, newLeaf.children);
				return splitNode(this, newLeaf);
			}
		}
		
		@Override
		public Object[] getChildren() {
			return children;
		}

		@Override
		public double[] getRectangles() {
			return rectangles;
		}
		
		@Override
		public void setCount(int count) {
			this.count = count;			
		}
		
		@Override
		public Rectangle findBounds() {
			double x0 = Double.POSITIVE_INFINITY;
			double y0 = Double.POSITIVE_INFINITY;
			double x1 = Double.NEGATIVE_INFINITY;
			double y1 = Double.NEGATIVE_INFINITY;
			for(int i=0;i<count;++i) {
				int ad = i * 4;
				double x0a = rectangles[ad++];
				double y0a = rectangles[ad++];
				double x1a = rectangles[ad++];
				double y1a = rectangles[ad++];				
				x0 = Math.min(x0, x0a);
				y0 = Math.min(y0, y0a);
				x1 = Math.max(x1, x1a);
				y1 = Math.max(y1, y1a);
			}
			return new Rectangle(x0, y0, x1, y1);
		}
	}				
	
	static Split splitNode(INode a, INode b) {
		double[] aRectangles = a.getRectangles(); 
		Object[] aValues = a.getChildren(); 
		double[] bRectangles = b.getRectangles();
		Object[] bValues = b.getChildren();
		double x0a = aRectangles[0];
		double y0a = aRectangles[1];
		double x1a = aRectangles[2];
		double y1a = aRectangles[3];
		double areaA = (x1a-x0a) * (y1a-y0a);
		double x0b = bRectangles[0];
		double y0b = bRectangles[1];
		double x1b = bRectangles[2];
		double y1b = bRectangles[3];
		double areaB = (x1b-x0b) * (y1b-y0b);
		int aCount = 1, bCount = 1;		
		
		int firstUnassigned = 1;
		loop:
		while(firstUnassigned < aValues.length) {
			int bestI = -1;
			double bestDiff = Double.NEGATIVE_INFINITY;
			boolean bestToB = false;
			for(int i=firstUnassigned,ad=firstUnassigned*4;i<aValues.length;++i) {
				double x0 = aRectangles[ad++];
				double y0 = aRectangles[ad++];
				double x1 = aRectangles[ad++];
				double y1 = aRectangles[ad++];
				double da = 
					(Math.max(x1a, x1) - Math.min(x0a, x0)) * (Math.max(y1a, y1) - Math.min(y0a, y0)) - areaA;
				double db = 
					(Math.max(x1b, x1) - Math.min(x0b, x0)) * (Math.max(y1b, y1) - Math.min(y0b, y0)) - areaB;
				double diff = Math.abs(da-db);
				if(diff > bestDiff) {
					bestI = i;
					bestDiff = diff;
					bestToB = db < da || (db==da && bCount < aCount);
				}
			}
		
			if(bestToB) {				
				rotate2(bRectangles, bValues, bCount, aRectangles, aValues, firstUnassigned, bestI);
				x0b = Math.min(x0b, bRectangles[4*bCount]);
				y0b = Math.min(y0b, bRectangles[4*bCount+1]);
				x1b = Math.max(x1b, bRectangles[4*bCount+2]);
				y1b = Math.max(y1b, bRectangles[4*bCount+3]);
				++bCount;
				++firstUnassigned;
				if(bCount == MAX_ENTRIES_AFTER_SPLIT) {
					while(firstUnassigned < aValues.length) {
						move(aRectangles, aValues, aCount, firstUnassigned);
						x0a = Math.min(x0a, aRectangles[4*aCount]);
						y0a = Math.min(y0a, aRectangles[4*aCount+1]);
						x1a = Math.max(x1a, aRectangles[4*aCount+2]);
						y1a = Math.max(y1a, aRectangles[4*aCount+3]);	
						++aCount;
						++firstUnassigned;
					}
					break loop;
				}				
			}
			else {				
				//System.out.println(aRectangles.length + " " + aValues.length + " " + aCount + " " + bCount + " " + firstUnassigned + " " + bestI);
				rotate(aRectangles, aValues, aCount, firstUnassigned, bestI);
				x0a = Math.min(x0a, aRectangles[4*aCount]);
				y0a = Math.min(y0a, aRectangles[4*aCount+1]);
				x1a = Math.max(x1a, aRectangles[4*aCount+2]);
				y1a = Math.max(y1a, aRectangles[4*aCount+3]);				
				++aCount;
				++firstUnassigned;
				if(aCount == MAX_ENTRIES_AFTER_SPLIT) {
					while(firstUnassigned < aValues.length) {
						move2(bRectangles, bValues, bCount, aRectangles, aValues, firstUnassigned);
						x0b = Math.min(x0b, bRectangles[4*bCount]);
						y0b = Math.min(y0b, bRectangles[4*bCount+1]);
						x1b = Math.max(x1b, bRectangles[4*bCount+2]);
						y1b = Math.max(y1b, bRectangles[4*bCount+3]);
						++bCount;
						++firstUnassigned;
					}
					break loop;
				}
			}
			
		}
		a.setCount(aCount);
		b.setCount(bCount);
		return new Split(x0a, y0a, x1a, y1a, x0b, y0b, x1b, y1b, b);
	}
	
	static void move(double[] array, Object[] oArray, int a, int b) {
		assert(a != b);
		oArray[a] = oArray[b];
		oArray[b] = null;
		a *= 4;
		b *= 4;
		for(int i=0;i<4;++i)
			array[a++] = array[b++];
	}
	
	static void move2(double[] array, Object[] oArray, int a, double[] array2, Object[] oArray2, int b) {
		oArray[a] = oArray2[b];
		oArray2[b] = null;
		a *= 4;
		b *= 4;
		for(int i=0;i<4;++i)
			array[a++] = array2[b++];
	}
	
	static void rotate(double[] array, Object[] oArray, int a, int b, int c) {
		if(a==b) {
			if(b==c)
				return;
			{
				Object temp = oArray[a];
				oArray[a] = oArray[c]; 
				oArray[c] = temp;
			}
			
			a *= 4;
			c *= 4;
			for(int i=0;i<4;++i) {
				double temp = array[a];
				array[a] = array[c];
				array[c] = temp;
				++a; ++c;
			}

		}
		else if(b==c) {
			{
				Object temp = oArray[a];
				oArray[a] = oArray[c]; 
				oArray[c] = temp;
			}
			
			a *= 4;
			c *= 4;
			for(int i=0;i<4;++i) {
				double temp = array[a];
				array[a] = array[c];
				array[c] = temp;
				++a; ++c;
			}
		}
		else {		
			{
				Object temp = oArray[b];		
				oArray[b] = oArray[a];
				oArray[a] = oArray[c];
				oArray[c] = temp;
			}
			
			a *= 4;
			b *= 4;
			c *= 4;
			for(int i=0;i<4;++i) {
				double temp = array[b];
				array[b] = array[a];
				array[a] = array[c];
				array[c] = temp;
				++a; ++b; ++c;
			}
		}
	}	
	
	static void rotate2(double[] array, Object[] oArray, int a, double[] array2, Object[] oArray2, int b, int c) {
		{		
			oArray[a] = oArray2[c];
			oArray2[c] = oArray2[b];
			oArray2[b] = null;
		}
		
		a *= 4;
		b *= 4;
		c *= 4;
		for(int i=0;i<4;++i) {			
			array[a] = array2[c];
			array2[c] = array2[b];
			array2[b] = 0.0;
			++a; ++b; ++c;
		}
	}	
	
	static void findNodeSeeds(double[] rectangles, Object[] values, Rectangle rect, Object value,
						  double[] newRectangles, Object[] newValues) {
		int bestI = -1;
		int bestJ = -1;
		double bestInefficiency = Double.NEGATIVE_INFINITY;
		for(int j=0;j<=rectangles.length;j+=4) {
			double x0b, y0b, x1b, y1b;
			if(j < rectangles.length) {
				x0b = rectangles[j];
				y0b = rectangles[j+1];
				x1b = rectangles[j+2];
				y1b = rectangles[j+3];
			}
			else {
				x0b = rect.x0;
				y0b = rect.y0;
				x1b = rect.x1;
				y1b = rect.y1;
			}
			double areaB = (x1b-x0b) * (y1b-y0b);
			for(int i=0;i<j;) {
				double x0a = rectangles[i++];
				double y0a = rectangles[i++];
				double x1a = rectangles[i++];
				double y1a = rectangles[i++];
				double inefficiency =
					(Math.max(x1a, x1b) - Math.min(x0a, x0b)) * (Math.max(y1a, y1b) - Math.min(y0a, y0b))
					- (x1a-x0a) * (y1a-y0a) - areaB;
				if(inefficiency > bestInefficiency) {
					bestI = i-4;
					bestJ = j;
					bestInefficiency = inefficiency;
				}					
			}
		}
		if(bestJ==rectangles.length) {			
			newRectangles[0] = rect.x0;
			newRectangles[1] = rect.y0;
			newRectangles[2] = rect.x1;
			newRectangles[3] = rect.y1;
			newValues[0] = value;
		}
		else {
			newValues[0] = values[bestJ/4];
			values[bestJ/4] = value;
			
			newRectangles[0] = rectangles[bestJ++];
			newRectangles[1] = rectangles[bestJ++];
			newRectangles[2] = rectangles[bestJ++];
			newRectangles[3] = rectangles[bestJ];		
			                      
			bestJ -= 3;
			rectangles[bestJ++] = rect.x0;
			rectangles[bestJ++] = rect.y0;
			rectangles[bestJ++] = rect.x1;
			rectangles[bestJ] = rect.y1;
			
		}
		
		if(bestI > 0) {			
			Object temp2 = values[0];
			values[0] = values[bestI/4];
			values[bestI/4] = temp2;
			
			double temp;
			temp = rectangles[0];
			rectangles[0] = rectangles[bestI];
			rectangles[bestI++] = temp;
			temp = rectangles[1];
			rectangles[1] = rectangles[bestI];
			rectangles[bestI++] = temp;
			temp = rectangles[2];
			rectangles[2] = rectangles[bestI];
			rectangles[bestI++] = temp;
			temp = rectangles[3];
			rectangles[3] = rectangles[bestI];
			rectangles[bestI++] = temp;			
		}
	}	
	
	INode root = new Leaf();
	
	public void search(Rectangle rect, IRectangleProcedure proc) {
		root.search(rect, proc);
	}
	
	public boolean intersects(Rectangle rect) {
		return root.intersects(rect);
	}
	
	public void add(Rectangle rect, Object obj) {
		Split split = root.add(rect, obj);
		if(split != null) {
			Node node = new Node();
			node.rectangles[0] = split.oldX0;
			node.rectangles[1] = split.oldY0;
			node.rectangles[2] = split.oldX1;
			node.rectangles[3] = split.oldY1;
			node.rectangles[4] = split.newX0;
			node.rectangles[5] = split.newY0;
			node.rectangles[6] = split.newX1;
			node.rectangles[7] = split.newY1;
			node.children[0] = root;
			node.children[1] = split.newNode;
			node.count = 2;
			
			root = node;
		}
	}
	
	static Random random = new Random();
		
	public static Rectangle randomRectangle() {
		double x = random.nextDouble();
		double y = random.nextDouble();
		double w = random.nextDouble()*0.1;
		double h = random.nextDouble()*0.1;
		return new Rectangle(x, y, x+w, y+h);
	}
	
	public static void main(String[] args) {
		Collection<Rectangle> rects = new ArrayList<Rectangle>();
		
		for(int i=0;i<1000;++i)			
			rects.add(randomRectangle());
		
		RTree tree = new RTree();
		for(Rectangle rect : rects) {
			tree.add(rect, rect);
			tree.root.findBounds();
		}
		
		
		
		for(int i=0;i<100;++i) {
			final Rectangle q = randomRectangle();
			
			int iCount = 0;
			for(Rectangle rect : rects)
				if(q.intersects(rect))
					++iCount;
			
			final int[] iCount2 = new int[] { 0 };
			tree.search(q, new IRectangleProcedure() {

				@Override
				public void call(double x0, double y0, double x1, double y1,
					Object value) {
					++iCount2[0];
					Rectangle r = (Rectangle)value;
					if(!r.intersects(q))
						System.out.println("Not really intersecting!");
					if( x0 != r.x0
					  ||y0 != r.y0
					  ||x1 != r.x1
					  ||y1 != r.y1)
						System.out.println("Value and key differ!" +
								"(" + x0 + " " + y0 + " " + x1 + " " + y1 + ") " +
								"(" + r.x0 + " " + r.y0 + " " + r.x1 + " " + r.y1 + ")");
				}
				
			});
			if(iCount != iCount2[0])
				System.out.println("Different iCount: " + iCount + " " + iCount2[0]);
		}
	}

}